An electrocardiography (ECG) device is a device that measures the electrical activity of the heart, and has been widely used to obtain biopotential signals of the heart and pulmonary system. To obtain biopotential signals, ECG electrodes coupled to an ECG device are applied to the skin of a user at various locations. However, proper placement and connection of the ECG electrodes are required for obtaining correct biopotential signals. In some existing ECG devices, ECG electrodes are embedded in a soft plastic material and separated from one another by a fixed spacing. Such ECG devices are attached to either the right side or the left side of the chest due to the short fixed electrode spacing. Besides, it may be difficult to apply the ECG devices to a body portion with a particular shape or curve such as the breast portion of a female user. Moreover, noise from myoelectricity or breathing may be detected and captured by the ECG devices, resulting in distortion of ECG signals.